| 摘要 |
PURPOSE:To realize a reduction of noise, by providing the band increment frequency property to each input signal according to the divided frequency band for transmission with a level compression and then providing the band attenuation frequency property at the reception side to each transmitted signal for an expansion of level. CONSTITUTION:The input signal sent from the terminal 26 is delivered to the output terminal 29 via the high-band increment type variable filter 27 and the low band increment type variable filter 28 each and at the same time supplied to the high-band filters 30 and 31 to produce the signal that controls the cut-off frequency of the filters 27 and 28 each. The signal provided with the level compression property and sent from the terminal 29 is recorded on the recording medium 34 which functions as a transmission line. The signal reproduced from the medium 34 is supplied to the low-band attenuation type variable filter 36 and the low-band filter 37 plus the high-band filter 38 each via the terminal 35, and the outputs of the filters 37 and 38 are supplied to the control circuits 39 and 40 to control the attenuation property of both the filter 36 and the high-band attenuation type variable filter 41. As a result, a signal having the same level of the reduced original input signal is obtained at the output terminal 42 with a big reduction given to the noise. |
